Document DataStore Sync State(RTD)

Added a CM-Handle data sync state description section under
Cps-Modelling -> NCMP-Modelling -> Basic Concepts -> Cm Handle

Issue-ID: CPS-1164
Change-Id: Ia53a1ccbacda388ec98a3de936af0913edad1c58
Signed-off-by: bmiklos <miklos.baranyak@est.tech>
diff --git a/docs/modeling.rst b/docs/modeling.rst
index acc430a..80cfdea 100644
--- a/docs/modeling.rst
+++ b/docs/modeling.rst
@@ -83,6 +83,16 @@
 
     These are stored as Anchors within CPS-Core.
 
+    - **Data-sync state** is the state of the data synchronization process of the CM-Handle
+
+        There are 3 possibles states: NONE_REQUESTED, UNSYNCHRONIZED, SYNCHRONIZED
+
+        **NONE_REQUESTED** indicates that the data sync is not requested by the user
+
+        **UNSYNCHRONIZED** indicates the cm-handle is waiting for the data sync watchdog operation to carry out the sync process
+
+        **SYNCHRONIZED** indicates the watchdog process has finished the data synchronization successfully
+
 - **Datastores** represent different views of the cm data.
 
     Datastores are defined for NCMP to access the CPS running or operational datastores. Currently supported datastores are: